1/1x3+1/3x5+1/5x7+...1/2001x2003=(1/1-1/3)/2+(1/3-1/5)/2+(1/5-1/7)/2+...+(1/2001-1/2003)/2=(1/1-1/3+1/3-1/5+1/5-1/7+...+1/2001-1/2003)/2=(1-1/2003)/2=2002/2003除以2=1001/2003孩子啊，我问的是用了什么法则！用了积化和差，合并同类项法则